Five friends, J, K, L, M and N, are a doctor, a lawyer, an artist, a teacher and an engineer, not necessarily in that order. There are two married couples among them, and one person is unmarried. Further:

1. J is a doctor and is married to the engineer.

2. M is married to K.

3. L is unmarried and is the lawyer.

4. K is the artist.

5. J and L are men; K, M and N are women.

Who is definitely a man?